Abstract

Objective: To screen adolescents with type 1 diabetes using ambulatory blood pressure monitoring (ABPM) in order to: 1) test the hypothesis that using a preset sleep time results in an over-diagnosis of abnormal nocturnal dipping in systolic BP, 2) assess the reproducibility of an abnormal nocturnal systolic BP dip.

Research Design and Methods: Aim 1: ABPM was reviewed from 53 adolescent patients with type 1 diabetes. Nocturnal dip in systolic BP calculated by actual sleep time was compared with that from a preset sleep time. Aim 2: BPM was reviewed from 98 patients using actual reported sleep time. Reproducibility of nocturnal dip in systolic BP was assessed in a subset of non-dippers.

Results: 1. The actual mean decline in nocturnal systolic BP was 11.6 ± 4.7%, while the mean fall in nocturnal systolic BP calculated using the preset sleep time was 8.8 ± 4.9% (p<0.0001). 2. Sixty four percent had a normal nocturnal decline in systolic BP (14.9 ± 3.1% mmHg), while 36 percent had an abnormal dip (5.7 ± 2.8% mmHg). Repeat ABPM performed on 22 of the 35 non-dippers revealed that only 36% had abnormal systolic dipping confirmed on the repeat ABPM.

Conclusions: The use of actual reported sleep time is required to accurately determine the nocturnal dip in systolic BP. Repeating ABPM in non-dippers is essential to confirm this abnormality.